gotta_goatsfast Posted June 13, 2010 Report Share Posted June 13, 2010 Guys, I'm in need of some help. I'll list what is currently done to the engine, my jetting, and the problem I'm having. The engine has, Toomey T5 pipes 30mm OKO carbs with pod filters Pro design head with 21cc domes V force 3 reed cages and timing was advanced 4 degrees The carbs currently have a 160 main, 52 pilot, and the factory needle with clip in middle. I don't have a sync tool, but both carb slides close and open at the same time to the eye. They click shut and open at the same time also. Idle enrichment screws both 1.5 turns out. My problem. I used to run a set of FMF gold series "fatty" pipes with powercore silencers and a trinity single carb intake with 33mm carb and airbox without lid. I recently pulled them off and went to Toomey T5 pipes/silencers and a pair of 30mm OKO carbs. With the old set up, the powerband started to pull about 6000rpm (trailtech tach) and would carry me to about 9000rpm, then it would run out of steam. Wanting to shift the main power up a little and increase my top end, I opted for my current set up. The powerband hits a lot harder, still around the 6000rpm range. Out of the powerband it actually rides really well. And when the tires don't spin, it pulls HARD from 6500-8000rpm. When the engine aproaches 7800-8200rpm it starts to miss and cut out. My old set up would have walked on this from 8000+rpm. Is this the nature of the T5s and OKO carbs? I was under the assumption that the T5s were a mid-top pipe and the FMFs where a midrange pipe, and that the dual carbs should provide more top end than a single. So, any input or help would be appreciated. Most of the ignition is new, and never had a problem before the parts swap. Is this in the jetting? I've heard of 30mm OKOs running the bowl dry, but they should provide more fuel than a single 33mm, and it cuts out with just a crack of the throttle into the top end or running through the gears. (more so with a greater engine load) Oh, and I should mention that I started with a 158 main, it seemed a little "zingy" and it cut out on top so I installed the 160s and had more "thump" to it but still cut out. It's raining now so I guess I'm done playing for today. Thanks in advance for the help! Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 13, 2010 Author Report Share Posted June 13, 2010 I would like to add that I run 93 octane fuel blended with Klotz R50 at a ratio of 32:1. Starting below the powerband, if I hold the throttle wide open it runs well to the 8000rpm mark where it coughs, misses, and cuts out. Quote Link to comment Share on other sites More sharing options...
hercalmighty Posted June 13, 2010 Report Share Posted June 13, 2010 Check your float heights, check and make sure your slides are opening 100%, check for air leaks, go up a size or two on the mains. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 13, 2010 Author Report Share Posted June 13, 2010 Anyone have an idea where the float height should be set at on an OKO 30mm carburetor? The slides both open all the way and reach full open at the same time. I did check for air leaks, but it won't hurt to do it again. I assumed 160 would be on the rich side considering other rider's specs with similar mods, altitude, and weather. Maybe I should order some 162 and 165 jets? Or is the top end sputter because it is running rich? Quote Link to comment Share on other sites More sharing options...
fastbanshee8 Posted June 13, 2010 Report Share Posted June 13, 2010 If you can, the next time it sputters on the top end, pull the chokes out, and see if it gets worse, or better. If it's better, you're lean, and if it's worse, your rich. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 14, 2010 Author Report Share Posted June 14, 2010 If you can, the next time it sputters on the top end, pull the chokes out, and see if it gets worse, or better. If it's better, you're lean, and if it's worse, your rich. damn, that trick slipped my mind. Its pretty predictable, as it runs HARD til that 8000rpm mark then it gives me problems. I'll warm the bike up and try that. The plug has a milk chocolate brown color, I assume this is acceptable? Should I do a plug chop even though something is still wrong, or will it tell me anything. Oh, and would I use a 28mm PWK float height for reference or are the OKOs set differently? Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 18, 2010 Author Report Share Posted June 18, 2010 Here's an update. I warmed the bike up and took it out. When revving it out, it will pull hard and not miss a beat until 8000rpm where it hits a wall and won't rev out anymore. The same run with the chokes pulled yeilds the same 8000rpm limit. I tried a 1-5 WOT run and it will do this on the top end of every gear, and I've coasted down a hill and then nailed it instantly and I hit that wall, so I'm pretty sure there's a good fuel supply as it shouldn't empty my bowls that quick. 160 main jet is the largest I have currently, and I thought this was on the large side. Should I order bigger? I could not find any leaks in my intake tract, but I'm still ordering new gaskets and installing them for added security. What rpm do T5s usually rev out to until they run out of steam? Thanks guys! Quote Link to comment Share on other sites More sharing options...
pr0blumz Posted June 18, 2010 Report Share Posted June 18, 2010 I read a topic on here a while back about a problem similiar to yours with the same carbs. If I remember correctly, he had to drill the fuel inlets on the inside of the carbs to a larger diameter because the bowls weren't filling fast enough. After he drilled them, the problem was gone. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 18, 2010 Author Report Share Posted June 18, 2010 That was something I considered also. But coasting with the clutch in at idle and then quickly running it to WOT within a few moments and still hitting that "wall" made me think otherwise. Could the bowl empty that quickly? Either way, anyone have info on where, how, or what to drill exactly? I want to exhaust all my options before turning the keys over to a shop. Quote Link to comment Share on other sites More sharing options...
pr0blumz Posted June 18, 2010 Report Share Posted June 18, 2010 Contact Rajun_Cajun on here. I think he was the one who had the problem. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 19, 2010 Author Report Share Posted June 19, 2010 I searched and found a little information on his solution for these carbs. I pm'd him so hopefully I'll get some insight back soon. When it runs hard and then falls on its face like that, would this be a lean or rich condition? It doesn't sneeze through the carbs, and choking it results in a slightly burbly midrange and still the 8000rpm stop. Is it possible this could be caused by an intake leak? Also, what should my float height be? Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 19, 2010 Author Report Share Posted June 19, 2010 Well, the day has been good and the banshee has finally bowed down and surrendered. I played with her orfices and touched her jugs a little.... then kicked her. She screamed and I rode'er hard til she was hot... Oh, I mean I cleaned the carbs, Installed new gaskets between the jugs, VF3s, and intake boots. Float height was adjusted from 24mm down to 19mm and 152 main/50 pilot installed with the air screw 1.25 turns out. There were two existing holes in the fuel inlet casting below the float needle seat that I reamed out to 1.5mm from a 1mm hole. It may be dumb luck, but she runs real hard now. Makes me want to call a few buddies who challenged me (stage 2 440ex and bolt on 660r raptor)and bust their egos. Anyways, the plug chop showed a milk chocolate brown ring slightly larger than 2mm around the base, but pretty consistent. It runs real good so I don't think I'll be straying much from this setup. I think once I get the C4 trans off of the work bench, I'll pull the 350 after riding season and build a +4mm longrod engine? Hmmm, atleast some port work. Which brings me to this question. What is the limits of the stock crankshaft when non welded/trued? What about welded and trued? Thanks for the help guys! Quote Link to comment Share on other sites More sharing options...
pr0blumz Posted June 20, 2010 Report Share Posted June 20, 2010 Do a leakdown test to make sure you don't have any air leaks or you will be rebuilding a lot sooner. Quote Link to comment Share on other sites More sharing options...
gotta_goatsfast Posted June 20, 2010 Author Report Share Posted June 20, 2010 Am I looking for air leaks within the intake system or within the crankcase? Quote Link to comment Share on other sites More sharing options...
camatv Posted June 25, 2010 Report Share Posted June 25, 2010 OKO'S ARE CHINESE JUNK THEY ARE SET UP TO RUN A 200CC CHINESE 4 STROKE PIECE OF CRAP. my 30mm pwk's have NO problem running my 421cc stock cylinder 5th gear pinned in the sand... check your jetting, check your spark,, if you change jetting and its still the same check your cap's and plugs. you may be loosing spark at the higher rpm. to check for no fuel in bowl run the bike till it sputter's turn off the fuel and kill the bike dump the carbs and measure the fuel in the bowl. should be a full bowl. OR remove the bowls and hook them up turn on your fuel you should have a LOT of fuel flow through the needle. Quote Link to comment Share on other sites More sharing options...
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